On a construction site it is often necessary to determine the volume of an object, for example of a stock pile or a hollow space like a pothole, a gap or a mine.
A conventional approach for determination of such volumes is scanning the object with a measuring device such as a laser scanner, a total station, a stereo camera or a set of fixedly mounted cameras. As from one station point only parts of the stock pile are measurable while other surface points are hidden, it is necessary to set up the measuring devices at at least three different positions with respect to e.g. the stock pile such that in combination the whole surface of the stock pile is measurable. The stock pile is captured from each station point, i.e. the spatial positions of surface points of the stock pile with respect to the measuring device are measured. Next, the point clouds resulting from three or more setups are combined and meshed. Then, the volume between the meshed surface and a ground surface is computed. A major disadvantage of such an approach is the fact that measuring devices such as a laser scanner, a total station, a stereo camera or a plurality of cameras are expensive hardware and have to be operated and positioned by a skilled user. Additionally, a setup of such a measuring device at three different positions and determining these positions at least relatively to each other is time consuming. However, in some cases this effort in time and money is somehow wasteful as the high accuracy of position measurement performed by a geodetic measuring device like a total station and the resulting high accuracy of the volume determination is not required, but a rather rough value for the volume would be sufficient.
For determining the volume of large objects or for covering multiple objects in large areas it is further known to use an unmanned aerial vehicle (UAV), equipped with a GNSS positions sensor and means for determining dimensional data of terrestrial objects.